The characterization of DNAJC3: elucidating the function of the TPR domains
- Mutsvunguma, Lorraine Zvichapera
- Authors: Mutsvunguma, Lorraine Zvichapera
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55874 , vital:26751
- Description: DNAJC3 is a novel member of the DNAJ family with two domains linked to co-chaperone functions, namely the tetratricopeptide repeat (TPR) and J domain. Out of the two domains, the TPR domains are the least characterized. Therefore, the aim of this study was to characterize and elucidate additional functions of DNAJC3 TPR domains through in silico, in vitro and ex vivo approaches. Through multiple sequence and structural alignment as well as electrostatic potential analysis, DNAJC3 TPR domain were found to be most similar to TPR-containing proteins with Hsp90 or Hsp70 independent functions. In vitro pull down assays illustrated that DNAJC3 TPR domains did not interact with either cytosolic Hsp90 and Hsp70 or Grp78 and Grp94 directly, however a potential indirect interaction with Grp94 and Hsp90 was observed in mammalian lysates, via pull down assays; suggesting the formation of a complex between the proteins mediated by a specific substrate. DNAJC3 TPR domains were found to bind indiscriminately to both native and heat denatured substrates in a dose dependent manner. DNAJC3 TPR domains bound to β-galactosidase with greater affinity than malate dehydrogenase (MDH), suggesting that DNAJC3 TPR domains might exhibit substrate specificity that has not been reported before. Preliminary ex vivo analysis of DNAJC3 in mammalian cells showed that induced stress conditions did not alter the cytosolic or endoplasmic reticulum (ER) localization, or levels of DNAJC3 protein, suggesting that the protein is not stress inducible. However, protein levels of DNAJC3 were dramatically reduced by Hsp90 inhibitor novobiocin at 500 μM. Transient knockdown DNAJC3 did not change the protein levels of either Grp78 or Grp94, but decreased the protein levels of Hsp70/Hsp90 organizing protein HOP. On the other hand, protein levels of DNAJC3 were increased in HOP depleted cells. In conclusion, this study was the first to experimentally demonstrate that DNAJC3 TPR domains do not interact directly with Hsp90, Hsp70, Grp78 or Grp94, and therefore DNAJC3 is unlikely to participate in traditional co-chaperone interactions with those proteins via its TPR domain. However, the J domain is known to interact with Grp78. The discovery that DNAJC3 TPR domains resemble that of TPR-containing proteins with functions independent of Hsp90 or Hsp70 suggests that DNAJC3 might link the Hsp70/Grp78 chaperone machinery to non co-chaperone related functions, which requires further analysis.
- Full Text:
- Date Issued: 2014
- Authors: Mutsvunguma, Lorraine Zvichapera
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55874 , vital:26751
- Description: DNAJC3 is a novel member of the DNAJ family with two domains linked to co-chaperone functions, namely the tetratricopeptide repeat (TPR) and J domain. Out of the two domains, the TPR domains are the least characterized. Therefore, the aim of this study was to characterize and elucidate additional functions of DNAJC3 TPR domains through in silico, in vitro and ex vivo approaches. Through multiple sequence and structural alignment as well as electrostatic potential analysis, DNAJC3 TPR domain were found to be most similar to TPR-containing proteins with Hsp90 or Hsp70 independent functions. In vitro pull down assays illustrated that DNAJC3 TPR domains did not interact with either cytosolic Hsp90 and Hsp70 or Grp78 and Grp94 directly, however a potential indirect interaction with Grp94 and Hsp90 was observed in mammalian lysates, via pull down assays; suggesting the formation of a complex between the proteins mediated by a specific substrate. DNAJC3 TPR domains were found to bind indiscriminately to both native and heat denatured substrates in a dose dependent manner. DNAJC3 TPR domains bound to β-galactosidase with greater affinity than malate dehydrogenase (MDH), suggesting that DNAJC3 TPR domains might exhibit substrate specificity that has not been reported before. Preliminary ex vivo analysis of DNAJC3 in mammalian cells showed that induced stress conditions did not alter the cytosolic or endoplasmic reticulum (ER) localization, or levels of DNAJC3 protein, suggesting that the protein is not stress inducible. However, protein levels of DNAJC3 were dramatically reduced by Hsp90 inhibitor novobiocin at 500 μM. Transient knockdown DNAJC3 did not change the protein levels of either Grp78 or Grp94, but decreased the protein levels of Hsp70/Hsp90 organizing protein HOP. On the other hand, protein levels of DNAJC3 were increased in HOP depleted cells. In conclusion, this study was the first to experimentally demonstrate that DNAJC3 TPR domains do not interact directly with Hsp90, Hsp70, Grp78 or Grp94, and therefore DNAJC3 is unlikely to participate in traditional co-chaperone interactions with those proteins via its TPR domain. However, the J domain is known to interact with Grp78. The discovery that DNAJC3 TPR domains resemble that of TPR-containing proteins with functions independent of Hsp90 or Hsp70 suggests that DNAJC3 might link the Hsp70/Grp78 chaperone machinery to non co-chaperone related functions, which requires further analysis.
- Full Text:
- Date Issued: 2014
The design, synthesis and antiplasmodial activity of a series of halogenated fosmidomycin analogues and hybrid drugs
- Authors: Afolayan, Anthonia Folake
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64370 , vital:28538
- Description: Malaria continues to be a devastating disease and a major cause of death in sub-Saharan Africa. With resistance against most of the available antimalarial drugs, there is a need for ongoing research and development of antimalarial agents. Fosmidomycin and its acetyl analogue FR900098 have been identified as potent inhibitors of Plasmodium falciparum, the causative agent of the most deadly form of malaria. Clinical trials of these agents have revealed poor absorption due to their high hydrophilicity. In the present studies the effect of halogenation of the acyl chain as well as the biological effect of extending the acyl sidechain was explored. This provided the basis on which fosmidomycin hybrids were designed to investigate the feasibility of hybrid extending into NADPH binding pocket. Synthesis of a series of halogenated FR900098 analogues was carried out in three stages. This included i) The introduction of the phosphonate group by reaction with 1,3dibromopropane in an Arbuzov reaction, ii) The introduction of a hydroxamate group by reaction of the propyl phosphonate by means of a nucleophilic substitution reaction with BocNHOBn and iii) The introduction of a halogenated acyl side chain on a protected fosmidomycin backbone. The synthesis of fosmidomycin-hybrids for which chloroquinefosmidomycin hybrids were used as the prototype, involved convergence of the two separately constructed moieties i.e. fosmidomycin and the quinoline moieties in a covalent linkage. The quinoline moiety was easily synthesized from the reaction of 4,7dichloroquinoline with 1,2-diamino ethane. The aminoquinoline so formed resulted in chloroquine-fosmidomycin hybrids 3.8 and 3.9 when reacted with halogenated FR900098 analogues. Antiplasmodial assays were conducted on the chloroquine-fosmidomycin hybrids and the halogenated fosmidomycin derivatives against the chloroquine resistant Gambian FCR-3 strain of P. falciparum. The most potent iodoacetyl fosmidomycin analogues 2.21 gave an IC50 value of 5.54 µM which is eight times more potent than the known antiplasmodial FR900098 which gave an IC50 value of 41.67 µM. All the halogenated FR900098 analogues showed better antiplasmodial activity than their non-halogenated derivatives. This indicated that the presence of halogens in the FR900098 analogues contributes to their biological Chapter 1 Literature review activity. The acetyl and propyl linked hybrids 3.8 and 3.9 showed potent antiplasmodial activity with IC50 values of 0.18 and 0.82 µM respectively. These were by far the most potent hybrids synthesized and provided leads for a new class of promising antimalarial agents. Preliminary E. coli DXR enzyme inhibition assays were carried out on the halogenated fosmidomycin analogues. The results showed good inhibition of the enzyme by the phosphonic acids of the chloroacetyl and chloropropyl analogues 2.1 and 2.2 respectively. Molecular modelling of the compounds on E. coli (PDB code: 2EGH) and P. falciparum (PDB code: 3AUA) DXR showed strong binding of the halogenated fosmidomycin analogues while the hybrids in the absence of docked NADPH showed minimum binding to the enzymes.
- Full Text:
- Date Issued: 2012
- Authors: Afolayan, Anthonia Folake
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64370 , vital:28538
- Description: Malaria continues to be a devastating disease and a major cause of death in sub-Saharan Africa. With resistance against most of the available antimalarial drugs, there is a need for ongoing research and development of antimalarial agents. Fosmidomycin and its acetyl analogue FR900098 have been identified as potent inhibitors of Plasmodium falciparum, the causative agent of the most deadly form of malaria. Clinical trials of these agents have revealed poor absorption due to their high hydrophilicity. In the present studies the effect of halogenation of the acyl chain as well as the biological effect of extending the acyl sidechain was explored. This provided the basis on which fosmidomycin hybrids were designed to investigate the feasibility of hybrid extending into NADPH binding pocket. Synthesis of a series of halogenated FR900098 analogues was carried out in three stages. This included i) The introduction of the phosphonate group by reaction with 1,3dibromopropane in an Arbuzov reaction, ii) The introduction of a hydroxamate group by reaction of the propyl phosphonate by means of a nucleophilic substitution reaction with BocNHOBn and iii) The introduction of a halogenated acyl side chain on a protected fosmidomycin backbone. The synthesis of fosmidomycin-hybrids for which chloroquinefosmidomycin hybrids were used as the prototype, involved convergence of the two separately constructed moieties i.e. fosmidomycin and the quinoline moieties in a covalent linkage. The quinoline moiety was easily synthesized from the reaction of 4,7dichloroquinoline with 1,2-diamino ethane. The aminoquinoline so formed resulted in chloroquine-fosmidomycin hybrids 3.8 and 3.9 when reacted with halogenated FR900098 analogues. Antiplasmodial assays were conducted on the chloroquine-fosmidomycin hybrids and the halogenated fosmidomycin derivatives against the chloroquine resistant Gambian FCR-3 strain of P. falciparum. The most potent iodoacetyl fosmidomycin analogues 2.21 gave an IC50 value of 5.54 µM which is eight times more potent than the known antiplasmodial FR900098 which gave an IC50 value of 41.67 µM. All the halogenated FR900098 analogues showed better antiplasmodial activity than their non-halogenated derivatives. This indicated that the presence of halogens in the FR900098 analogues contributes to their biological Chapter 1 Literature review activity. The acetyl and propyl linked hybrids 3.8 and 3.9 showed potent antiplasmodial activity with IC50 values of 0.18 and 0.82 µM respectively. These were by far the most potent hybrids synthesized and provided leads for a new class of promising antimalarial agents. Preliminary E. coli DXR enzyme inhibition assays were carried out on the halogenated fosmidomycin analogues. The results showed good inhibition of the enzyme by the phosphonic acids of the chloroacetyl and chloropropyl analogues 2.1 and 2.2 respectively. Molecular modelling of the compounds on E. coli (PDB code: 2EGH) and P. falciparum (PDB code: 3AUA) DXR showed strong binding of the halogenated fosmidomycin analogues while the hybrids in the absence of docked NADPH showed minimum binding to the enzymes.
- Full Text:
- Date Issued: 2012
Intellectualisation of African languages with particular reference to isiXhosa
- Authors: Maseko, Pamela
- Date: 2011
- Subjects: Xhosa language -- Study and teaching -- South Africa , Language and education -- South Africa , African languages
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58035 , vital:27035
- Description: The research explores the relationship between language and education, and motivates for the intellectualisation of African languages, isiXhosa in particular, and for their use in education. The main rationale behind this is that access to, and success in education can largely be realised if that education is mediated in one’s first language. The thesis discusses works of prominent scholars who have written on the subject - relating cognitive abilities and achievement in education to language in which that education is offered. The lack of terminology in new domains in African languages as barrier to mother tongue education is laid bare by looking specifically at the history of intellectualisation of isiXhosa, from the missionaries in the 1820s up to the new endeavours as recently as 2008. Terminologies that were developed during the Bantu Education era, where development of isiXhosa and other indigenous African languages was accelerated in order to respond to the demands of moedertaal-onderwys (mother tongue education) are surveyed, and the process of their development analysed. Three main terminology lists developed during this period are analysed against terminology development principles, approaches and methods that are seen as a measure to ensure quality terminology development. The efforts of the development of isiXhosa during the post-apartheid South Africa, especially the government-driven initiatives, are also critiqued even though these are not as effective and as extensive, especially in education. The result of this analysis is that African languages and isiXhosa in particular, can be used in scientific disciplines and at the highest levels of education. Its grammar is advanced, and its lexicon is extensive such that new concepts that need to be named can be named, using appropriate term creation strategies. There are also technological tools such as WordSmith tools that can be used that can advance its development, ensuring that the concept represented in the newly-created term is precise, concise and appropriate in terms of its discipline. Therefore it is argued that, in the interim, terminologies should be developed, in various subjects, to support learning, which at this stage is mediated in English, for those students who have other languages as mother tongue. Those terminologies that have been developed in the various historical periods should be collated, revised and brought into the classrooms. The thesis argues that real intellectualisation of isiXhosa and other African languages rests on the use of these languages in classrooms and lecture halls, and in the value that all role players place on these languages.
- Full Text:
- Date Issued: 2011
- Authors: Maseko, Pamela
- Date: 2011
- Subjects: Xhosa language -- Study and teaching -- South Africa , Language and education -- South Africa , African languages
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58035 , vital:27035
- Description: The research explores the relationship between language and education, and motivates for the intellectualisation of African languages, isiXhosa in particular, and for their use in education. The main rationale behind this is that access to, and success in education can largely be realised if that education is mediated in one’s first language. The thesis discusses works of prominent scholars who have written on the subject - relating cognitive abilities and achievement in education to language in which that education is offered. The lack of terminology in new domains in African languages as barrier to mother tongue education is laid bare by looking specifically at the history of intellectualisation of isiXhosa, from the missionaries in the 1820s up to the new endeavours as recently as 2008. Terminologies that were developed during the Bantu Education era, where development of isiXhosa and other indigenous African languages was accelerated in order to respond to the demands of moedertaal-onderwys (mother tongue education) are surveyed, and the process of their development analysed. Three main terminology lists developed during this period are analysed against terminology development principles, approaches and methods that are seen as a measure to ensure quality terminology development. The efforts of the development of isiXhosa during the post-apartheid South Africa, especially the government-driven initiatives, are also critiqued even though these are not as effective and as extensive, especially in education. The result of this analysis is that African languages and isiXhosa in particular, can be used in scientific disciplines and at the highest levels of education. Its grammar is advanced, and its lexicon is extensive such that new concepts that need to be named can be named, using appropriate term creation strategies. There are also technological tools such as WordSmith tools that can be used that can advance its development, ensuring that the concept represented in the newly-created term is precise, concise and appropriate in terms of its discipline. Therefore it is argued that, in the interim, terminologies should be developed, in various subjects, to support learning, which at this stage is mediated in English, for those students who have other languages as mother tongue. Those terminologies that have been developed in the various historical periods should be collated, revised and brought into the classrooms. The thesis argues that real intellectualisation of isiXhosa and other African languages rests on the use of these languages in classrooms and lecture halls, and in the value that all role players place on these languages.
- Full Text:
- Date Issued: 2011
Myth, Music & Modernism: the Wagnerian dimension in Virginia Woolf's Mrs Dalloway and the waves and James Joyce’s Finnegans Wake
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
The healer's art : Cape Nguni diviners in the townships of Grahamstown
- Authors: Hirst, Manton Myatt
- Date: 1991
- Subjects: Healers -- South Africa , Nguni (African people) -- Social life and customs , Divination -- South Africa , Medicine, Magic, mystic, and spagiric -- South Africa , Nguni (African people) -- Religion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:2084 , http://hdl.handle.net/10962/d1001601
- Description: This is a study of Cape Nguni diviners practising in the townships of Grahamstown where, during the 1970s, there was a large and active concentration of diviners treating clients from the locality, the rural areas and even the large urban centres further afield. The study situates local diviners in the socio-economic, cultural and religious context of contemporary township Iife during the 1970s (see chapter 1 and section 2.1). The personalities and socio-economic circumstances of diviners (and herbalists) are described as well as their case-loads, the various problems they treat, the relations between them and their clients, the economics of healing and the ethics pertaining to the profession (see chapter 2) . Chapter three focuses on the various problems and afflictions - which are largely of an interpersonal nature - suffered by those who are eventually inducted as diviners and the ritual therapy this necessarily entails. Here we see how the diviner, what Lewis (1971) terms a 'wounded healer', becomes an expert in interpersonal and social relations as a result of suffering problems - largely connected to the family but not necessarily limited to it - in interpersonal relations and that require a ritual, and thus social, prophylaxis. The main theoretical argument is that the diviner, qua healer, functions as a hybrid of Levi-Strauss' s bricoleur and Castaneda's 'man of knowledge' artfully combining the ability of the former to invert, mirror or utilise analogies from linguistics to make everything meaningful and the ability of the latter to creatively bend reality . The diviner's cosmology is described in terms of a 'handy', limited but extensive cultural code/repertoire of signs, symbols and metaphors that is utilised in getting the message across to others and in which animals bear the main symbolic load (see chapter 4). This leads logically to a reappraisal of Hammond-Tooke's (1975b) well-known model of Cape Nguni symbolic structure particularly in so far as it pertains to the way in which diviners classify animals, both wild and domestic (see section 4.6). A striking evocation and confirmation of the view argued here, namely of the diviner as bricoleur/'man of knowledge', is contained in chapter five dealing with an analysis of the diviner's 'river' myth and the context, form and content of the divinatory consultation itself. Finally, the conclusions, arising out of this study of contemporary Cape Nguni diviners in town, are evaluated in the ligrht of Lewis's (1966, 1971, 1986) deprivation hypothesis of spirit possession (see chapter 6)
- Full Text:
- Date Issued: 1991
- Authors: Hirst, Manton Myatt
- Date: 1991
- Subjects: Healers -- South Africa , Nguni (African people) -- Social life and customs , Divination -- South Africa , Medicine, Magic, mystic, and spagiric -- South Africa , Nguni (African people) -- Religion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:2084 , http://hdl.handle.net/10962/d1001601
- Description: This is a study of Cape Nguni diviners practising in the townships of Grahamstown where, during the 1970s, there was a large and active concentration of diviners treating clients from the locality, the rural areas and even the large urban centres further afield. The study situates local diviners in the socio-economic, cultural and religious context of contemporary township Iife during the 1970s (see chapter 1 and section 2.1). The personalities and socio-economic circumstances of diviners (and herbalists) are described as well as their case-loads, the various problems they treat, the relations between them and their clients, the economics of healing and the ethics pertaining to the profession (see chapter 2) . Chapter three focuses on the various problems and afflictions - which are largely of an interpersonal nature - suffered by those who are eventually inducted as diviners and the ritual therapy this necessarily entails. Here we see how the diviner, what Lewis (1971) terms a 'wounded healer', becomes an expert in interpersonal and social relations as a result of suffering problems - largely connected to the family but not necessarily limited to it - in interpersonal relations and that require a ritual, and thus social, prophylaxis. The main theoretical argument is that the diviner, qua healer, functions as a hybrid of Levi-Strauss' s bricoleur and Castaneda's 'man of knowledge' artfully combining the ability of the former to invert, mirror or utilise analogies from linguistics to make everything meaningful and the ability of the latter to creatively bend reality . The diviner's cosmology is described in terms of a 'handy', limited but extensive cultural code/repertoire of signs, symbols and metaphors that is utilised in getting the message across to others and in which animals bear the main symbolic load (see chapter 4). This leads logically to a reappraisal of Hammond-Tooke's (1975b) well-known model of Cape Nguni symbolic structure particularly in so far as it pertains to the way in which diviners classify animals, both wild and domestic (see section 4.6). A striking evocation and confirmation of the view argued here, namely of the diviner as bricoleur/'man of knowledge', is contained in chapter five dealing with an analysis of the diviner's 'river' myth and the context, form and content of the divinatory consultation itself. Finally, the conclusions, arising out of this study of contemporary Cape Nguni diviners in town, are evaluated in the ligrht of Lewis's (1966, 1971, 1986) deprivation hypothesis of spirit possession (see chapter 6)
- Full Text:
- Date Issued: 1991
The development of athletics in South Africa: 1814 to 1914
- Authors: Coghlan, Douglas Victor
- Date: 1987
- Subjects: Athletics -- South Africa -- History
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60785 , vital:27830
- Description: The purpose of this study was to record the development of athletics in South Africa from 1814 to 1914. This period was chosen because sport and athletics originated and developed a social institution during that time and the First World brought progress to a temporary halt, after which there were many new developments. The Cape Colony became British in 1814, and it was British influence that played such a dominant role in the social history of the period.
- Full Text:
- Date Issued: 1987
- Authors: Coghlan, Douglas Victor
- Date: 1987
- Subjects: Athletics -- South Africa -- History
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60785 , vital:27830
- Description: The purpose of this study was to record the development of athletics in South Africa from 1814 to 1914. This period was chosen because sport and athletics originated and developed a social institution during that time and the First World brought progress to a temporary halt, after which there were many new developments. The Cape Colony became British in 1814, and it was British influence that played such a dominant role in the social history of the period.
- Full Text:
- Date Issued: 1987
The biology of Clarias Gariepinus (Burchell, 1822) in Lake Sibaya, Kwazulu, with emphasis on its role as a predator
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
The chemistry of the wattle tannins
- Authors: Roux, David Gerhardus
- Date: 1953
- Subjects: Tannin plants , Tannins , Wattles (Plants)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:4492 , http://hdl.handle.net/10962/d1013098
- Description: Four species of acacia of Auatralian origin are associated with the wattle industry in South Africa. Black wattle, Acacia mollissima willd., is the most important of these and is today almost exclusively cultivated. The tree grows successfully only in a limited area of rich soil and high rainfall and is easily affected by adverse conditions caused by insect pests, frost damage and drought. Expansion of the area under cultivation is therefore, not feasible, although the world demand for vegetable extracts far exceeds the available supply. The remaining species such as green (Acacia decurrrens willd.) and silver wattles (Acacia dealbata Link.) possess many desirable characteristics which resist such adverse factors. Their barks, however, give reddish extracts, which are considered unsuitable for tannery usage because of the red colour they impart to the leather. Hybridisation studies, involving the crossing of green and silver wattle with the black, and aimed at produc1ng progenies containing many of the desirable characterlstics of the parent plants, are thus a natural result and have been in progress for a considerable period. Summary, p. i.
- Full Text:
- Date Issued: 1953
- Authors: Roux, David Gerhardus
- Date: 1953
- Subjects: Tannin plants , Tannins , Wattles (Plants)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:4492 , http://hdl.handle.net/10962/d1013098
- Description: Four species of acacia of Auatralian origin are associated with the wattle industry in South Africa. Black wattle, Acacia mollissima willd., is the most important of these and is today almost exclusively cultivated. The tree grows successfully only in a limited area of rich soil and high rainfall and is easily affected by adverse conditions caused by insect pests, frost damage and drought. Expansion of the area under cultivation is therefore, not feasible, although the world demand for vegetable extracts far exceeds the available supply. The remaining species such as green (Acacia decurrrens willd.) and silver wattles (Acacia dealbata Link.) possess many desirable characteristics which resist such adverse factors. Their barks, however, give reddish extracts, which are considered unsuitable for tannery usage because of the red colour they impart to the leather. Hybridisation studies, involving the crossing of green and silver wattle with the black, and aimed at produc1ng progenies containing many of the desirable characterlstics of the parent plants, are thus a natural result and have been in progress for a considerable period. Summary, p. i.
- Full Text:
- Date Issued: 1953